FIG. 1 is a timing chart of signals for the line inversion method adopted by the conventional liquid crystal display. FIG. 1 shows that, for all the scan lines, the polarities of voltages applied to the data lines and the common lines are repeatedly inverted with time in the liquid crystal display driven by a color sequential method. In the color sequential method, sub-frames of three primary colors, e.g., red, green, and blue, are configured to constitute a complete frame, and thus the driving frequency of each sub-frame is 180 Hz. However, the scan lines on the panel of the LCD display are switched in only a small portion of a sub-frame time (<5 μs), and the other portion of the sub-frame time is configured to rotate the liquid crystal molecules in specific positions to turn on a backlight. Moreover, a scan time of a scan line needs to be shortened in order to reduce the possibility of the liquid crystal molecules reacting synchronically as a result of differences between the scan times of different scan lines, which leads to the degradation of brightness of the display panel driven by a line-sequential mode. Therefore, the scan time for each scan line must be shortened.
In the condition that the above scanning method is adopted by a driving configuration of the common line voltage swing shown in FIG. 1, and the LCD display is operated by a line inversion method, a common voltage on the common lines may be incapable of inverting with time and thus resulting in the problem of unstable charging of a pixel unit.
For solving the aforesaid problems, in general, the LCD display in FIG. 1 is substituted by an LCD adopted with a frame inversion method. FIG. 2 is a timing chart of the signals of the frame inversion method adopted by a conventional LCD. FIG. 2 shows when the LCD is driven by the color sequential method, the voltages on the scan lines, data lines, and common lines vary with time. As shown in FIG. 2, in the frame inversion method, the polarity of a common line voltage inverses once between two consecutive frames such that the common line voltage reaches a stable value before the scan line start being switched on, and thus the stability of charging state of the pixel unit is ensured.
However, compared with other LCDs, the flicker problem of the LCD with the frame inversion method is more serious. The LCD implementing a frequency of up to 300 Hz may mitigate the flicker problem. If the reaction time of the liquid crystal molecules can't keep up with the frequency, brightness degradation is inevitable.
For solving the aforesaid problem, an LCD and a driving method thereof are provided.